Concentration of sylvinite ores



Patented Dcc. 5, 1944 2.864.520 CONCENTRATION or SYLVINITE onus Allen T.Cole and Wesley M. Houston, Lakeland, Fla.. assignors to MineralsSeparation North American Corporation, New York, N. Y., a corporation ofMaryland No Drawing. Application June 23, 1943, Serial No. 491.948

17 Claims.

This invention relates to the concentration or separation of the valuesfrom soluble ores. More particularly, it relates to the separation ofsylvite (potassium chloride, KCl) from sylvinite ores such as, forexample, those found in the Carlsbad district of New Mexico.

The invention resides in improved methods of effecting the separation ofthe desired sylvite from such ores by froth flotation, skin flotation,agglomeration tabling and other methods involving wet stratificationwith the use of appropriate agents which efiect the separation of thesylvite from the other oreconstituents.

It is already known that sylvite can be recovered from a saturatedsolution of the soluble constituents of sylvinite ore in accordance withwell-established concentration operations by using as a collector analiphatic amine containing a straight chain hydrocarbon group of atleast 7 carbon atoms, or the salts of such amines resulting from theircombination with water-soluble acids.

The general objects of the present invention are to produce concentratesof the desired sylvite which are of high commercial grade, with highpercentages of recovery, with economy in the use of reagents and withreliable and easily controlled operation of the plant. These objects areattained by the processes embodying the present invention which arehereinafter described.

The methods of the present invention are the result of the discoverythat greatly improved results, as to grade and recovery of the desiredsylvite and as to control of operations, can be obtained by the use asauxiliary agents in conjunction with the aforesaid straight chain alkylamines used as collectors,of certain cellulosic materials as hereinafterdefined, which are dispersible in aqueous media.

The straight chain alkyl amines useful as collectors for sylvite, theaction of which is improved by the concurrent use of said dispersiblecellulosic materials as auxiliary agents, include the followingaliphatic primary amines: n-heptylamine, n-octylamine, n-nonylamine,n-decylamine, n-undecylamine, n-dodecylamine, n-tet- =raclecylamine,n-hexadecylamine, n-heptadecylamine, n-octadecylamine, andn-octadecenylamine. The lower members of this series may be added to theore pulp in the form of the free base or as the salts formed by theircombination with acids which are themselves relatively devoid of surfaceactive properties, such for example, as hydrochloric acid, nitric acid,acetic acid, etc. The higher members of the series, being much lesssoluble, are generally used in the form of their more soluble salts.

These amine collectors may be used individually or as mixtures. Themixtures need not necessarily consist only of aliphatic primary aminesor their salts but may also contain varying proportions of aliphaticsecondary and tertiary amines or their salts, such as are commonly foundin commercial products. For example, the

product of Armour and Company sold under the designation "Am. Ac. 1180-0isvery suitable and is understood to consist of approximately 73%mono-octadecylamine acetate, about 24% mono-hexadecylamine acetate,together with small quantities of secondary and tertiary amine acetates.Another suitable commercial product is that sold by E. I. du Pont DeNemours 81 Company, Inc., as "D. P. 243 which is a 50% aqueous paste oftechnical laurylamine hydrochloride understood to contain approximately18% octylamlne hydrochloride, 10% decylamine hydrochloride, laurylaminehydrochloride, 17% myristylamine hydrochloride, and traces of secondaryand tertiary amines.

Cellulose, as is well known, is a carbohydrate which occurs abundantlyin plants. Those cellulosic materials which have been found useful arethose materials in whichthe inherent cellulose structure is largelyretained as in unmodified cellulose and in substituted cellulosiccompounds, such as, for example, cellulose esters, cellulose ethers,cellulose xanthates, cellulose carbamates, etc. The term cellulosicmaterial" as used herein and in the claims is to be taken as includingmaterials of the types Just mentioned but as exeluding such advanceddegradation products, as, for example, glucose, which we have found tobe non-effective in the process. The aqueous dispersions of thecellulosic materials of our invention may be true molecular dispersions(solutions) or colloidal dispersions of large molecular aggregates. Thecellulosic materials may be added to the flotation brine as aqueousdispersions in water or brine, or they may be added as solutions ordispersions in organic solvents to form an aqueous dispersion in theflotation brine.

Among the cellulose materials which may be sufficiently dispersed inaqueous media to function effectively when added to the ore-pulp are theesters known as cellulose xanthates, and the ethers known as methylcellulose and ethyl cellulose. Methyl cellulose, which is commerciallyavailable as Methocel," manufactured by the Dow Chemical Company, is avery effective auxiliary agent in the concentration of sylvite from itsores.

Other cellulosic materials within the scope of the invention may be moredifiicult to disperse in aqueous solutions, for example, celluloseacetate, cellulose nitrate (nitrocellulose) and cellulose acetatehydrogen phthalate. In many cases such materials can be used effectivelyfor the purposes of the invention if they are first dissolved ordispersed in a suitable organic liduid, and the organic liquid solutionof the celluloslc material. then agitated with the ore pulp. As oneexample, dioxane has been found to be very effective as an organicliquid dispersant. In some cases it may be advantageous to add smallamounts of emulsifying agents to the organic liquid solution of thecellulosic material to aid in the subsequent dispersion of the materialin the aqueous brine. In the case of any particular cellulosio materialwhich is difllcult to disperse, a few simple tests with various solventsor mixtures of solvents may be necessary to determine the best means ofobtaining a suitable dispersion in the brine.

We have found that cellulose dissolved in concentrated zinc chloridesolution acts as an auxiliary reagent in the flotation of 'sylvite withamine acetate. While this process is not comrnerclally important due tothe inhibiting effect 'ofthe large amount of zinc chloride present. itis an interesting illustration of the use of an unmodified cellulosicmaterial according to the teachings of our invention.

The following specific examples of embodiments of the invention show, bycomparison with the comparative tests in which no ceilulosc material wasused, the advantages to be obtained from the use of these materials asauxiliary agents.

In practicing the methods of the present invention. desllming of thesylvinite ore is desirable; and it is also sometimes desirable to add afrothing agent, such as pine oil, in addition to the collector and theauxiliary agent, when the desired mineral is to be concentrated by frothflotation, or a petroleum oil such as fuel oil when concentration is tobe effected by tabling.

Comparative test A.'Sylvinite ore from Carlsbad, NewMexico, was crushedso that it would pass through a -mesh screen, and was then deslimed andground so that it would pass through a lib-mesh screen, after which itwas made into a pulp of about solids with a saturated solution of oreconstituents. Reagents,

dlings to be returned to the flotation circuit and further valuesrecovered therefrom. The re-v agents used were Am. Ac. 1180-C" 1.00 lb.and pine oil 0.2 lb., both per ton of ore treated. The results were asfollows:

Per cent Per cent KCl reoov- Product weight KCl ery Feed 100.0 81.2100.0 Concentrate ill. 6 00. 9 45. 4 Mid f 6. 0 8d 1 l6. 6 Middling-i.8. 9 e2. 6 17. s Talling 64. 4 7. 2 14. 8 ims s. 1 88. 2 6. 4

Example 1.--This-operation was identical with Comparative test A exceptthat methyl cellulose was employed as an auxiliary agent. 0.8 lb. perton of ore of this material (Dow Chemical Company's "Methocel) was addedto the pulp in the form of a 5% aqueous solution in addition toa,se4,sao

the reagents used in Comparative test A. The results were as follows:

Per cent Percent KCireoow weight KCl ery swan.-. 100.0 :04 100.Concentrate. as s 91.1 15. Middling-Z. a s 01. s 1. Middllng-l. a 1 21.54. 'Iailing sac 1.4 2. Slime 0.1 45.8 0.

It will be noted that the use of themethyl cellulose in conjunction withthe other reagents, as is shown by comparison of Example 1 withComparative test A, improved the recovery by 30.4% (75.8% KCl whenmethyl cellulose was used as against 45.4% KClrecovery without it) andgrade remained about the same (91.1% as against 90.9%).

Example 2.The ore, procedure and reagents were the same as in Example 1except that instead of methyl cellulose the auxiliary agent wascellulose acetate, 0.8 lb. per ton of are added to the pulp in the formof a 3% solution in dioxane. The results were as follows:

Per cent Per cent KC] duct weight KC! recovery Feed 100.0 80. 1 100.0Concentrate 21. 8 87. 8 63. n Mlddling 2 6.2 08.8 11.0 Mlddllng-l l0. 286. 0 l2. s Taillug t8. 6 4. 4 8. 0 Blime 4. 3 24. 0 3. 4

By comparison of Example 2 with Comparative test A, it will be seen thatthe addition of the cellulose acetate increased recovery by 18.2% with aslight loss in grade amounting to but 3.1%.

Example 3.The ore, procedure and reagents were the same as in Example 1except that the auxiliary agent was cellulose acetate hydrogenphthalate, in the amount of 1.6 lbs. per ton of ore, added to the pulpas a 5% solution in dioxane. The results were as follows:

, Per cent Per cent KC] weight KC! recovery Feed 100. 0 26. 9 100. 0Concentrate. 26. 0 92. 0 s6. 4 Middllng-2. 2. 0 43. 8 3. 2 Middling-l.7. 8 l0. 1 2. 7 Tailing 00.1 2. 2 a 0 Slime 6. 6 l7. 6 a. 7

By comparison of Example 3 with Comparative test A, it will be seen thatthe addition of the cellulose compound increased recovery by 40% whilegrade was better by 1.1%.

Example 4.-The ore, procedure and reagents were the same as in Example 1except that the auxiliary agent was cellulose xanthate, in the amount of1.6 lbs. per ton of ore, added to the pulp as a 3% aqueous colloidalsolution. The results were as follows:

By comparison of Example 4 with Comparative test A. it will be seen thatthe addition of cellulose xanthate increased recovery by 11% while gradewas better by 1.3%.

Comparative test B.- -This test will serve as a basis of comparison forExample and together therewith illustrates use of the invention with.table concentration. The ore was the same as used in Comparative test A.It was crushed to pass a 6-mesh screen and then the plus 35-meshfraction was screened out and deslimed in saturated brine. It was'thenmade into a pulp in which the ratio of brine to ore was 111.88 by weightand conditioned with the reagent for one minute. The sole reagent was"Am. Ac. 1180C", 0.5 lb. per ton of dry ore. The conditioned pulp wasfed to a shaking table with a saturated aqueone solution of soluble oreconstituents. The sylvite concentrate was recovered at the side of thetable and rejected constituents went off at the Example 5.-The ore,procedure and reagent 10 Slim were the same as in Comparative test Bexcept that 0.4 lb. per ton of ore of methyl cellulose was added to thepulp as an auxiliary agent in the form of a 5% aqueous solution. Theresults were as follows:

By comparison of Example 5 with Comparative Test B, it will be seen thatthe addition of methyl cellulose increased recovery by 35.4% while therewas a slight decrease in grade of but 2.6%.

Comparative test C.--Sylvinite ore from the same locality as that usedin Comparative test A was prepared and subjected to flotation asdescribed in that test except that it was initially ground to pass a28-mesh instead of a 10-mesh screen. The sole reagent used in this test,however, was-Du Ponts DP243 in the amount of 0.9 lb. per ton of dry ore,introduced as a 5% aqueous solution. The results were as follows:

Example firi-The ore, procedure and reagent were the same asin.Comparative test C except that 0.9 lb. per ton of oreof methyl cellulosewas Per cont Per cent KC! weight K P odutt recovery l Concentrate.

By comparison of Example 6 with Comparative test C it will be seen thatthe use of methyl cellu- "lose in conjunction with "DP-243 increasedrecovery 11% while grade remained practically the same.

otherwise than as specifically illustrated and described. What isclaimed is: v 1. The improvement in the method of separating sylvitefrom a pulp containing it which comprises subjecting said pulp to a.concentrating process employing a collector selected from the groupconsisting of aliphatic amines containing a straight chain hydrocarbongroup of at least 7 carbon atoms and their soluble salts formed by theircombination with acids which are relatively devoid of surface activeproperties, which resides in distributing in said pulp a useful amountof an auxiliary agent consisting of a molecular or colloidal dispersionof a cellulosic material in aqueous media, and thereafter subjecting thepulp to a separation treatment to remove the desired sylvite.

2. A method as set forth in claim 1, wherein the pulp is formed fromsylvinite ore and a substantially saturated aqueous solution of thesoluble ore constituents.

3. A method as set forth in claim 1, wherein the sylvinite ore issubstantially deslimed before the collector and the auxiliary agent areadded.

4. A method as set forth in claim 1, wherein the separation treatment isa froth-flotation treatment in a froth-flotation machine.

5. A method as set forth in claim 1, wherein the separation treatment isby means of a shaking table. I

6. A method as set forth in claim 1, wherein a frothlng agent is used inconjunction with the collector and auxiliary agent and the separation ofthe sylvite is effected by froth flotation.

'7. A method as set forth in claim 1, wherein a petroleum oil is used inconjunction with the collector and auxiliary agent, the sylviteagglomerated and the agglomerates separated.

8. A method as set forth in claim 1, wherein the cellulosic material isa cellulose ester.

9. A method as set forth in claim 1, wherein the cellulosic material iscellulose acetate.

10. A method as set forth in claim 1, wherein the cellulosic material iscellulose xanthate.

11. A method as set forth in claim 1, wherein the cellulosic material isa cellulose ether.

12. A method as set forth in claim 1, wherein the cellulosic material isa water-soluble substituted cellulose compound.

13. A method as set forth in claim 1, wherein the cellulosic material ismethyl cellulose.

14. A method as set forth in claim 1, wherein 4 a,se4,sao

'sylvite.

1'7. A method as set forth in claim 1, wherein octadecylamine acetate isused as the collector in conjunction with as petroleum oil andseparation is effected by tsblinz treatment to re- 5 move the sylvite.

ALLEN T. COLE. WESLEY M. HOUSTON.

